Yes, in most of Hildenborough you can, and the neighbours are proving it at a steady clip. Every listed building in the village sits in the lowest grade. There is one conservation area. Planning applications arrive by the hundred each year. The rules bite on a minority of houses, and that minority is easy to spot before you buy.
Historic England lists 46 buildings in the area, and all 46 are Grade II. There are no Grade I buildings and none at Grade II*. Grade II is the entry tier, but listing still covers the whole building, inside and out, so most alterations to a listed home need listed building consent on top of any planning permission. Replacing windows, knocking through a wall or changing a roof covering can all fall into that. Doing the work first and asking afterwards is a criminal offence, not a paperwork slip, which is a sentence every buyer of a pretty old cottage should read twice.
There is one conservation area, named Hildenborough. Inside it, the council takes a closer interest in anything that changes how a property looks from the street, and some work that would be routine elsewhere needs permission. Demolition inside a conservation area needs consent, and trees are protected too, so the ambitious garden clearance is also a conversation with the council.
The village is not short of people trying. Across April 2024 to June 2026 there were 1,099 planning applications in the area, and 508 of them came in the last twelve months. That is live proof that Hildenborough's homeowners are busy adding kitchens, loft rooms and garages, and that planning here is a normal part of owning a house rather than a rare ordeal. Whether any particular scheme succeeds is a separate question the application count cannot answer.
For most homes outside the conservation area and not on the listed register, permitted development rights allow modest rear extensions, loft conversions and outbuildings without a full planning application, within national size limits. Anything bigger, anything on a listed building, or anything that changes the street view inside the conservation area moves into full planning permission. Before making an offer on a house you plan to extend, check whether it is listed, whether it sits inside the conservation area, and whether a previous owner has already used up the permitted development allowance on an earlier extension.
Freedom to extend in Hildenborough is middling: most houses carry no heritage constraint at all, but the listed buildings and the conservation area are exactly where the planning conversation gets longer. Buy outside them and the builder's diary becomes the main obstacle.